DESCRIPTION: (Adapted from the Applicant's Description) This project is concerned with the epidemiology of NPC and HCC. Dr. Yu will implement and complete a cohort study of 60,000 Chinese aged 45-64 years in Singapore. The primary aim is to definitively establish the causal relationship between ingestion of Chinese salted fish and similar foods and NPC development as suggested by previous case-control studies. A broader aim is to establish a stable cohort for the long term study of the relationship of dietary and other environmental determinants to cancer and other chronic diseases. Other NPC related projects include a case-control study in Shanghai (an intermediate risk region) and a case-control study in Taiwan (a moderately high risk region). These two studies are a part of the applicant's continuing attempt to define NPC etiology in Chinese in whom incidence rates vary by 20-fold. The applicant will also continue her collaboration with biochemists, Drs. Steven Tannenbaum and Joseph Landolph, to systematically search for the carcinogenic compound(s) in Chinese salted fish that give rise to NPC in humans. Future research in HCC etiology will mainly involve a cohort study of middle-aged men in Shanghai (a high risk population) and a case-control study among black and white residents of Los Angeles County (a low risk population). A goal of both studies is to elucidate the independent and interactive roles of hepatitis B virus (HBV), hepatitis C virus (HCV), alcohol, and tobacco in the pathogenesis of HCC. The Shanghai study has the additional goal of investigating the role of dietary aflatoxin in hepatocarcinogenesis while the Los Angeles study also aims to examine the relationship between hormone use and HCC development.